Sign up for Medicare during your Initial Enrollment Period, which starts three months before the month you turn 65 and lasts for seven months total

Your Initial Enrollment Period is a one-time window that opens automatically when you reach 65. It runs from three months before your birthday month through three months after it — that is seven months total. If you miss this window, you can still enroll later, but you may pay higher premiums for the rest of your life, and there will be gaps in your coverage.

You do not have to wait until your birthday month itself. Many people enroll as soon as the period opens, three months before they turn 65, so their coverage starts on the first day of their birthday month. This timing prevents any lapse in health insurance.

If you are already receiving Social Security benefits before age 65, Medicare will enroll you automatically. You will receive your Medicare card in the mail about two weeks before your coverage begins. If you are not yet receiving Social Security, you will need to enroll yourself through Medicare.gov, by phone, or in person at a Social Security office.

Key Takeaways

  • Your Initial Enrollment Period lasts seven months: three months before your 65th birthday, the month you turn 65, and three months after.
  • If you enroll before your birthday month, your coverage typically starts on the first day of that month.
  • Missing your Initial Enrollment Period can result in permanent premium penalties and coverage gaps that are difficult to fix.
  • If you are already on Social Security, Medicare enrolls you automatically; otherwise, you must enroll through Medicare.gov, by phone at 1-800-MEDICARE, or at your local Social Security office.
  • Special enrollment periods exist if you lose employer coverage or move to a new state, allowing you to enroll outside the standard window without penalty.

What happens if you miss your Initial Enrollment Period

If you do not enroll during your seven-month window and you do not have other may have access to coverage, you will face a late enrollment penalty. This penalty is a permanent increase to your Part B and Part D premiums — it does not go away after a few years. The longer you wait to enroll after your Initial Enrollment Period ends, the higher the penalty grows.

You will also have gaps in coverage. If you go without Medicare Part B or Part D coverage, you are responsible for the full cost of doctor visits, hospital stays, and prescription drugs during those months. These costs can add up quickly and are not retroactively covered once you do enroll.

There are limited exceptions. If you had creditable coverage — health insurance through a current employer, a spouse's employer, or certain other sources — you may not owe a penalty. You will need to show proof of that coverage when you enroll. If you are unsure whether your coverage counts as creditable, contact your insurance company or call Medicare at 1-800-MEDICARE before your Initial Enrollment Period ends.

Special enrollment periods outside your birthday window

You can enroll in Medicare outside your Initial Enrollment Period if you experience certain life changes. These Special Enrollment Periods last two months and do not carry a penalty, even if they occur years after you turn 65.

The most common reason for a Special Enrollment Period is losing employer health coverage. If you or your spouse retires or loses a job, or if your employer stops offering health insurance, you have two months from the date of that change to enroll without penalty. You will need to provide proof — a letter from your employer or insurance company stating the date coverage ended.

Moving to a new state also triggers a Special Enrollment Period. If you relocate and your current Medicare plan no longer serves your new address, you can change plans during the two-month window following your move. Other may have access to events include losing Medicaid coverage, becoming a U.S. citizen, or having a change in your immigration status.

Timing your enrollment to avoid coverage gaps

The exact month your coverage starts depends on when you enroll. If you enroll before your birthday month, your Part A and Part B coverage typically begins on the first day of your birthday month. If you enroll during your birthday month, coverage usually starts the first day of the following month. If you enroll after your birthday month, there may be a one-month delay.

To avoid any gap, enroll as soon as your Initial Enrollment Period opens — three months before you turn 65. This gives Medicare time to process your information and issue your card. You will receive your Medicare card in the mail roughly two weeks before your coverage date.

If you are still working and covered by your employer's health plan, you can delay Part B enrollment without penalty as long as your employer has 20 or more employees. This is called delayed enrollment. However, you must enroll in Part A at 65 even if you are still working, because Part A has no employer coverage exception. Once you leave your job or your employer coverage ends, you have eight months to enroll in Part B without penalty.

How to enroll during your Initial Enrollment Period

You have three main ways to enroll: online through Medicare.gov, by phone, or in person. The online method is often the fastest. Go to Medicare.gov, create an account, and follow the enrollment steps. You will need your Social Security number and basic information about your health coverage history.

To enroll by phone, call 1-800-MEDICARE (1-800-633-4227). Representatives are available seven days a week. Have your Social Security number and information about any current health coverage ready. The call usually takes 15 to 20 minutes.

You can also visit your local Social Security office in person. Bring your Social Security card, proof of citizenship or legal residency, and information about your current coverage. Offices are open Monday through Friday, and you can find yours at ssa.gov or by calling 1-800-772-1213.

Choosing your coverage type during enrollment

When you enroll, you will choose between Original Medicare (Part A and Part B) and a Medicare Advantage plan (Part C). Original Medicare is run by the federal government and covers hospital care, doctor visits, and some preventive services. Medicare Advantage is offered by private insurance companies and bundles Part A, Part B, and usually Part D (prescription drug coverage) into one plan.

You will also need to choose a Part D plan (prescription drug coverage) if you select Original Medicare. If you choose a Medicare Advantage plan that includes drug coverage, you do not need a separate Part D plan. If you do not enroll in Part D when you first become may be able to access and you do not have other creditable drug coverage, you will pay a penalty when you eventually enroll.

Your Initial Enrollment Period is the time to compare plans and choose the one that fits your doctors, hospitals, and medications. You can change your plan later during the Annual Enrollment Period (October 15 to December 7 each year), but starting with the right choice saves you time and money.

If you are still working at 65

If you are still employed and your employer offers health insurance, you do not have to enroll in Medicare Part B right away. You can delay Part B enrollment as long as your employer has 20 or more employees and you are covered under the employer plan. However, you must still enroll in Part A at 65, because Part A does not have an employer coverage exception.

When you eventually leave your job or your employer coverage ends, you have eight months to enroll in Part B without a late penalty. This is called the Special Enrollment Period for employer coverage. After those eight months, any delay in enrolling will result in a permanent penalty.

Part D (prescription drug coverage) follows the same rule as Part B. If your employer plan includes drug coverage that is at least as good as Medicare's standard coverage, you can delay Part D without penalty. Once your employer coverage ends, you have 63 days to enroll in Part D without a penalty.

Frequently Asked Questions

What if I turn 65 in the middle of the month?

Your Initial Enrollment Period still runs for seven months: three months before the month you turn 65, your birth month, and three months after. If you enroll before your birth month, coverage usually starts on the first day of that month, regardless of the exact date of your birthday.

Can I enroll in Medicare before I turn 65?

You can enroll starting three months before your 65th birthday. You cannot enroll earlier. If you are younger than 65 and have end-stage renal disease, ALS, or have been on Social Security disability for two years, you may be may be able to access for Medicare before 65 — contact Medicare to learn about your options.

Do I lose my current health insurance when I enroll in Medicare?

You should contact your current insurance provider to cancel your coverage once Medicare begins. Do not let both policies overlap for an extended period, as you will pay premiums for both. Some employers automatically end coverage when you become may be able to access for Medicare.

What if I am not a U.S. citizen?

You must be a U.S. citizen or a lawful permanent resident who has lived in the United States for at least five consecutive years to enroll in Medicare. If you are not yet a permanent resident, contact Medicare at 1-800-MEDICARE to discuss your situation.

Can I change my mind after I enroll?

Yes. During your Initial Enrollment Period, you can change your plan choices. After your Initial Enrollment Period ends, you can make changes during the Annual Enrollment Period (October 15 to December 7) or if you experience a may have access to life event. Changes made during the Annual Enrollment Period take effect January 1.